Contaminants may exist in gaseous streams. In many industrial or commercial applications the contaminants must be at least partially separated or removed. Contaminants may be in the form of combustion bi-product, or may be dust, liquid, organic matter, or other particulates from various sources.
Various techniques exist to attempt particle removal from gaseous streams. For example, filtration, washing, centrifugation or vortexing, agglomeration, and electrostatic precipitation are used for particle removal. Filtration, for example, passes the gaseous stream through a mechanical filter that may selectively trap particles of a given size. Filtration requires that the filter be cleared or replaced, thus disturbing the operation of the device with which the gaseous stream is associated. Washing includes the introduction of another liquid into the gaseous stream the cleanser. However, the cleanser must be further treated or removed from the gaseous stream.
Centrifugation, also referred to as vortexing or cyclone separation, separates particles from the gas stream by way of centrifuge, or spinning particles in the gaseous stream. During centrifugation, a rotational velocity caused in the gas stream facilitates separating particles depending upon size. However, centrifugation is limited by particle size and mass constraints because the smaller the particle, the less effective the centrifugation becomes. To increase the rotational velocity, and thus alter the particle size which may be collected, the gaseous stream must be introduced at an increased velocity. Increased velocities result in greater pressure drops and more mechanical wear on the hardware, reducing the overall operating efficiency and longevity of the device.
Agglomeration allows the mixing and adhesion or grouping of particles together, thus increasing the size and mass, allowing for further methods for removal. Occasionally, agglomeration includes the addition of a sorbent having qualities that encourages adhesion by the particles to be removed. The agglomerated particles, including the sorbent and unwanted particles, may be removed, for example, by electrostatic precipitation as discussed below, mechanical or chemical filtration, centrifugation, or the like. However, agglomeration techniques decrease the effectiveness and efficiency of the additional particle removal method. Thus, there exists a need to improve agglomeration efficiencies.
Electrostatic precipitators electrically charge the unwanted particles, which are then passed near oppositely charged collecting electrodes that collect the charged particles. The unwanted particles may then either be collected from the collecting electrodes or, alternatively, directed by way an electrical field away from the gas outlet for later collection.
Each of these above-discussed methods of particle separation have certain disadvantages. For example, the above-discussed methods often result in a pressure drop in the gaseous stream, decreasing the efficiency of gas flow. Additionally, some of the above-discussed methods are limited by particle size or type, and do not provide a flexible, adjustable method of removing particles from a gaseous stream. Furthermore, the mechanical vortexing or centrifugation techniques require increasing the gas velocity introduced to increase the rotational velocity, which increases the resultant pressure drop and increases wear in the hardware.
Thus, there is a need for systems and methods that induce swirl in particles.
There is a further need for systems and methods that may flexibly, adjustably, and selectively separate, remove, or mix particles from a gaseous stream by way of inducing swirl to particles in the gaseous stream.